Two new species and one new record of Neoperla (Plecoptera, Perlidae) from Guangxi Zhuang Autonomous Region, China

Abstract Three species of the Neoperlamontivaga group are described from Guangxi Zhuang Autonomous Region of southern China, including two new species, N.falcatatasp. nov. and N.shangsiensissp. nov., and a new record for Guangxi: N.bilineata Wu & Claassen, 1934. Illustrations and color images are provided for the three species mentioned above, and the new species is compared with related congeners in the group. Notes on the distribution of the Neoperla species known from Guangxi are also given.


Introduction
Neoperla Needham, 1905, of the subfamily Perlinae (Plecoptera, Perlidae), is one of the most species-rich and widely distributed stonefly genera, with at least 271 species worldwide (DeWalt et al. 2020). To date, 104 Neoperla species have been reported in China, comprising about 38% of species in the genus (Yang and Li 2018;DeWalt et al. 2020). The N. montivaga species group was first proposed by Zwick (1983) and currently includes 119 species worldwide (Yang and Li 2018;DeWalt et al. 2020;Mo et al. 2020a). In the present paper, we describe two new species and provide one new record of Neoperla from Guangxi, southern China. The three species are members of the Neoperla montivaga species group as defined by Zwick (1983), because of the incomplete sclerotization on the ventral surface of the aedeagal tube. The distribution and number of Neoperla species in cities of Guangxi are also presented.

Materials and methods
Specimens were collected using an aerial net or by light traps with white lamps and stored in 75% ethanol. The holotype of the new species and other studied specimens are deposited in the Insect Collection of the Henan Institute of Science and Technology (HIST), Xinxiang, China and in the National Museum Prague (NMP), Czech Republic, as indicated in the text. Specimens were examined with the aid of a Leica M420 dissecting microscope and the color illustrations were made with a Leica S8APO. Aedeagi were everted using the cold maceration technique of Zwick (1983), and terminology follows Sivec et al. (1988). The map (Fig. 10) was prepared using a base map of the Guangxi Zhuang Autonomous Region downloaded from the standard map service of the online government service platform of the Ministry of Natural Resources, People's Republic of China (http://bzdt.ch.mnr.gov.cn/; map number GuiS (2017)47).
Distribution. China (Guangxi, Sichuan). Ecology. The Jiangdi Village is located in the northeast of the Multinational Autonomous County of Longsheng, Guangxi, and is bordered by the Xing'an, Lingchuan and Ziyuan counties of Guangxi and by Chengbu County of Hunan Province. The   Wu & Claassen, 1934 (male) A terminalia after being cleared, dorsal view B terminalia after being cleared, lateral view C aedeagus, lateral view D aedeagus, dorsal view E aedeagus, ventral view. Scale bars: 1.0 mm. Wu & Claassen, 1934 was originally described from the Sichuan Province of southwest China, without full eversion of the aedeagus.  made a complementary description, including that of the completely everted aedeagus. In the present study, two males of this species from Guangxi agree well with original and complementary illustrations and descriptions of the head pattern, the dorsal aspects of the terminalia and the aedeagus (Wu and Claassen 1934;Wu 1938;. We provide additional illustrations (Figs 1, 2) for aiding the recognition of this species from the Guangxi Zhuang Autonomous Region of southern China. Diagnosis. This species is characterized by a median dark brown oval area on the head. The aedeagus is sickle-shaped, mostly covered with mixed armatures of spines and spinules. Females of this species have a small truncate tab-like subgenital plate of sternum 8.

Remarks. Neoperla bilineata
Description. Adult habitus (Figs 3, 4, 5A, 6C). Body color brown. Head brown, with a dark brown subtrapezoidal stigma on anterior part of frons and a distinct median dark brown oval area covering the posterior ocelli; mouthparts brown, palpi paler, antennae dark brown; biocellate, the distance between ocelli ca. 1.5× the diameter of each ocellus; head slightly wider than pronotum. Pronotum rectangular, brown, with scattered darker rugosities; anterior corners sharp, posterior corners rounded. Wings brownish and transparent, veins dark brown; legs brown except femora yellow-brown at base; cerci dark brown.
Male (Figs 3, 4A, 5, 6A). Forewing length 10.0-10.5 mm. Hindwing length 8.3-8.8 mm. Posterior process of tergum 7 trapezoidal, covered with many basiconic sensilla. Tergum 8 with a tongue-shaped upcurved process, with many basiconic sensilla at apex. Tergum 9 with two paramedial patches of long hairs, without sensilla patches. Hemitergal processes of tergum 10 sclerotized, slender, finger-like, S-shaped: basally incurved, curved outward medially but incurved again apically, nearly extending to tongue-shaped process of tergum 8 (Fig. 5B, D, E). Aedeagus mostly membranous, sickle-shaped (Figs 5C, F, 6A). Aedeagal tube plump, straight, distinctly sclerotized basally and dorsally, with many spinules on dorsal surface (Fig. 5F). Aedeagal sac ca. 2.0× as long as tube, membranous, strongly curved ventrad, forming an open loop with a blunt tip; ventral surface fully armed with spinules; dorsal surface of basal half covered with brownish spines; distal half mostly covered with larger brown dorsal spines before spinous apex (Figs 5C, F, 6A). Etymology. The name refers to the sickle-shaped aedeagus. The Latin "falcatus" means sickle-shaped. ing stoneflies were: Amphinemura hamiornata Li & Yang, 2008, Neoperla shangsiensis sp. nov., N. yentu Cao & Bae, 2007, N. yao Stark, 1987, an unidentified Neoperla sp. found only as a female, Rhopalopsole cestroidea Li, Murányi &Gamboa, 2017, andTogoperla perpicta Klapálek, 1921.  Li & Zhang, 2014 from Henan Province, central China. However, the new species can be easily separated from the latter by the markings on the head and pronotum (see Li and Zhang 2014: fig. 1a). The new species can also be distinguished from N. nigromarginata by the hemitergal processes of tergum 10 and details of tergum 7. In N. falcatata, the hemitergal processes of tergum 10 are longer and nearly extend to the process of tergum 8, and tergum 7 only bears a trapezoidal posterior process, whereas in N. nigromarginata the hemitergal processes of tergum 10 are short and only extend to the posterior margin of tergum 9, and tergum 7 has a pair of upraised, nipple-shaped processes in addition to the distal subquadrate process. Additionally, both species can be distinguished by details of the aedeagal armature (see Li and Zhang 2014: figs 1d, 2). Additionally, the aedeagal sac of N. nigromarginata bears paired apical flagella, whereas in the new species the aedeagal sac lacks the apical flagella.

Remarks. The new species shares a similar shape of the aedeagus with Neoperla nigromarginata
Finally, the female subgenital plates of the two species have different details. In N. falcatata, the posterior margin of the subgenital plate is truncate, while in N. nigromarginata the posterior margin of the subgenital plate has a slightly emarginate tip. Diagnosis. This species is characterized by head with a median dark-brown rectangular marking covering the posterior ocelli, with a pair of posterior wing-like extensions. In the male, the aedeagus is characterized by a short ventral spinulose lobe, a pair of small dorsal spinulose lobes, and a low ventroapical lobe fully armed with spines.

Neoperla shangsiensis
Description. Adult habitus (Fig. 7A, B). Body color brown. Head brown, with a dark brown fishtail stigma on anterior part of frons and a distinct median dark-brown rectangular marking covering posterior ocelli, with a pair of posterior wing-like extensions; mouthparts brown, palpi paler, antennae dark brown; biocellate, the distance between ocelli slightly wider than the diameter of one ocellus; head slightly wider than pronotum. Pronotum trapezoidal, brown, with scattered darker rugosities; anterior corners sharp, posterior corners rounded. Wings brownish and transparent, veins dark brown; legs brown except femora yellow-brown at base; cerci brown.
Male (Figs 7-9). Forewing length ca. 12.0 mm. Hindwing length ca. 10.4 mm. Posterior process of tergum 7 small, triangular, covered with many marginal basiconic sensilla. Tergum 8 without a process but covered by a small median spine patch. Tergum 9 with a pair of patches of basiconic sensilla and long hairs. Hemitergal processes of tergum 10 sclerotized, finger-like, bent ventrally in basal half, apical half slightly outcurved, tapering to an acute tip and nearly extending over tergum 9 (Figs 7C,  8A, B). Aedeagus mostly membranous, nearly straight (Figs 8C-F, 9). Aedeagal tube plump, straight, sclerotized basally and dorsally, with a pair of dorsoapical spinose lobes (Figs 8E,F,9). Aedeagal sac about as long as tube, membranous, with a blunt trumpet-shaped tip; basoventral lobe distinctly shorter than corresponding width of sac, cylindrical, nearly parallel with aedeagus, with spinose apex; apical dorsal lobe small, triangular in lateral view, covered with a group of long spines; most of surface armed with dense spinules; apical portion covered with large spines, ventral spines smaller 9).
Female. Unknown. Etymology. The species name refers to the Shangsi County, where the type locality is located.

Remarks.
The new species belongs to the Neoperla oculata species complex of the montivaga species group as defined by Zwick (1983Zwick ( , 1986, because of the wide lobe of tergum 7 and the four lobes of the aedeagus. The new species seems closely related to N. furcomaculata Kong & Li, 2016 from Hainan Province in having similar terminalia and aedeagal structures. However, the new species is easily distinguishable from the latter by the distinctively pigmented head pattern. Additionally, both species can be distinguished by the details of the aedeagal structure (see Kong et al. 2014: figs. 5d, 6). In N. shangsiensis, the paired dorsoapical spinose lobes of the aedeagal tube are higher and larger, and the ventroapical lobe of the aedeagal sac is distinctly enlarged. In N. furcomaculata, the paired dorsoapical spinose lobes of the aedeagal tube are obviously lower and smaller, and the ventroapical part of the aedeagal sac is not enlarged and is without a lobe. In addition, the basoventral lobe of aedeagal sac of the new species is nearly parallel with the aedeagal tube and distinctly shorter than the corresponding width of the sac, whereas in N. furcomaculata the basoventral lobe of the aedeagal sac is perpendicular to the aedeagal tube and subequal in length to the width of the corresponding portion of the sac.

Concluding remarks
Guangxi Zhuang Autonomous Region is located in southern China. The Region borders Guangdong Province to the east, Beibu Gulf to the south and Hainan across the sea, Yunnan Province to the west, Hunan Province to the northeast, and Guizhou Province to the northwest. The Region also borders Vietnam to the southwest. To date, 24 species of Neoperla known from Guangxi had been studied, mainly by Wu (1948), Yang and Yang (1990), Du (1998), Du and Sivec (2004), Li et al. (2013Li et al. ( , 2020, Wang et al. (2013aWang et al. ( , 2013b, Yang et al. (2017), and Mo et al. (2019Mo et al. ( , 2020a. The type locality of one of these species, Neoperla quadrispina Li, Mo & Wang, 2020, was misspelled in the original description and it should be revised to Pingtianshan National Forest Park. In the checklist of Yang and Li (2018), N. han Stark, 1987 was recorded from Guangxi by mistake, but this species do not occur in Guangxi (Stark 1987;Du et al. 1999;Wang et al. 2013;Mo et al. 2020b). The stonefly genus Neoperla primarily occurs in the Baise, Fangchenggang, Guilin, Laibin and Nanning cities of Guangxi (Fig.  10). There are famous reserves or parks in these five cities, including Cenwanglaoshan National Natural Reserve, Damingshan National Natural Reserve, Dayaoshan National Nature Reserve, Huaping National Nature Reserve, Jinhuacha Nature Reserve, and Shiwandashan National Forest Park. The genus Neoperla is widely distributed in Guangxi, which nearly covers two-thirds of the region. It has been poorly collected in southeast Guangxi. In the present study, two additional new species of Neoperla are described and one new species record of the genus for Guangxi is provided.